農業用水管理と連動した河川堤外地の自然再生型ランドスケープデザインに関する考察

抄録

Primary purpose of this study is to practically optimize the process through which landscape design will contribute to restoring natural environment in riverbed land in urbanized areas. The following points are identified through the survey and analysis of flora and related environment in “Natural Zone” of Ishikawa River Park in Osaka Prefecture. Controlled flooding of extra agricultural water into riverbed land and maintenance activities of irrigation channels including excavation of sediment were incorporated as a vegetation control measure. The results of flora survey indicated that although stable communities of perennial species have been established in major riverbed land due mostly to dry condition, some induced disturbance of vegetation such as maintenance practice of irrigation channels would be an effective measure to reset the environmental conditions and promote diversity in species composition. It was also indicated that difference in function and maintenance practice of irrigation channel affects the extent and frequency of those artificial disturbance that turns to be a measure of vegetation control. On the other hand, since natural disturbance is not precisely predictable, it is necessary to carefully trace the post disturbance changes in flora and to reflect those on the process of planning and design of riverbed landscape.